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You have to write the paragraphs. I can't write them for you or I break what brainmass is all about - helping not do your work.

I suggest a quick internet search on "Apollo 13".

http://nssdc.gsfc.nasa.gov/planetary/lunar/ap13acc.html

Newton's first law of motion:

An object at rest will remain at rest and an object in motion will continue in motion with a constant velocity (that is, constant speed in a straight line ) unless it experiences a net external force (or resultant force).

Consider Apollo 13 in free space with no resultant forces... The point between the earth and the moon where the force of attraction to the moon is equal and opposite to the force of attraction to the earth. Given that the capsule has a velocity at this point it will coast in space with the same velocity and no propulsion system is required to keep this velocity with no retardation forces present. Galileo also wrote several decades before Newton, "Any velocity once imparted to a moving body will be rigidly maintained as long as the external causes of retardation are removed." A now classic experiment, one done on air tables in the college general physics lab, is the examination of motion of a light disk on a column of air. Here the disk has a "constant" velocity neglecting air friction and coasts until retardation or net resultant force is applied.

Newton's second law:

The acceleration of an object is ...

Solution Summary

This solution is provided in 1,075 words. It provides a reference to help with the problem, and discusses in detail all three of Newton's laws and how they relate to the Apollo 13 flight.